Carwin, 11-0, has beaten everyone put in front of him, six by knockout or TKO and five by submission. His longest fight is 2 minutes and 11 seconds.

At 6-foot-2 and 260 pounds, with a stellar collegiate wrestling background, he would pose the toughest power and style challenge of Lesnar’s short mixed martial arts career.

Carwin was scheduled to face Cain Velasquez (6-0) on Oct. 24 at the Staples Center in Los Angeles in what UFC president Dana White had billed as a match to determine Lesnar’s next challenger. Instead, Lesnar vs. Carwin will headline a show that would include the return of Tito Ortiz, facing UFC Hall of Famer Mark Coleman.

"Brock is ready to go now and wants to fight," said White. "Carwin makes the most sense. He’s 11-0, and he’s been kicking the [expletive] out of everybody. [Gabriel] Gonzaga destroyed [Mirko] Cro Cop and he [Carwin] totally destroyed Gonzaga. Plus, he hates Brock Lesnar."

Sources outside the UFC confirmed Velasquez was told on Thursday that the fight was off because Carwin was being moved to face Lesnar. Velasquez was told he would be given a new opponent for Oct. 24.

Carwin has been the most vocal of the UFC heavyweight contenders in criticizing Lesnar (4-1). After retaining his title over Frank Mir in the biggest MMA event in U.S. history at UFC 100 on July 11, Lesnar got in Mir’s face, causing officials to jump between them. He then flipped off the audience that booed him heavily the entire fight, insulted UFC’s main sponsor, Bud Light, and did a pro wrestling-style interview.

"The flipping off of the fans that just lined your pocket with millions of dollars is just lame," Carwin said in the week after UFC 100. "He may be a champion, but he has a long ways to go before he earns the respect of a champion. The fans are why we do this, Brock. This sport is not about fat paychecks and drama. It is about hard work and sacrifice for a shot to do what you did [that] night. It doesn’t matter how much money you make if you can’t earn your peers’ respect and the respect and love of the greatest sporting fans in the world."

Carwin also played the pro wrestling card – the profession Lesnar garnered celebrity status in between 2002-2004 – which seemed to get under Lesnar’s skin when played in prior matches by Heath Herring and Mir.

"We have no scripts in this sport, no predetermined earning amount and no predetermined outcomes," Carwin wrote. "It doesn’t matter if you win or lose, it matters how you win or lose."

"He hates Brock Lesnar," said White. "It’s going to be two huge guys going at it. He’s got the power to knock anybody out and he’s got great wrestling too. He’s one of the guys that has the size to match up with Brock, too. This is one of those fights that could be wild. Someone’s going to get their head knocked off."

Carwin, 34, is probably the closest athletic equivalent to Lesnar in MMA.

Both are huge men with strong backgrounds in wrestling as well as heavy powerlifting. Lesnar was Division I national wrestling champion at the University of Minnesota in 2000. Carwin competed at the Division II level for Western State College in Gunnison, Colo., where he was 1999 national champion, and was twice a Division II All-America linebacker in football.

Simply through his background, Carwin would pose the toughest style threat to Lesnar to date. If his wrestling is good enough to stop Lesnar from taking him down, Carwin would appear to have an advantage and pack the harder punch, even though neither are great technical strikers. More likely in a standing battle with guys of that power, it would come down to who landed first.

From a credentials standpoint, Division I wrestling is a level above Division II, but that is also a decade ago. In their UFC 96 match in March, Gonzaga took Carwin down, and Lesnar is bigger, stronger and a better wrestler than Gonzaga. Carwin is untested on his back and also completely untested in terms of conditioning for a long match.

Nate Marquardt, who has trained with Carwin, noted the Carwin trains in high altitude in Colorado, and doesn't think cardio would be an issue. Lesnar’s cardio for a long fight is also untested for someone who is near his size and has wrestling ability, although he did go the full 15 minutes in a 2008 win over Heath Hering.

Carwin’s wrestling ability is such that even if he is taken down, he wouldn’t likely be controlled and dominated without being able to get up through sheer power, like Lesnar was able to do in his fights with Herring and the second fight with Mir.

Carwin is most dangerous for a strong right hand, which felled Gonzaga, Christian Wellisch and Neil Wain in his three UFC outings. His record for quick wins is impressive, but it also has included only one top level heavyweight, Gonzaga. He showed both good and bad signs in that fight. He was taken down immediately, and had his nose broken from a punch, which required surgery that kept him out of action for several months. But seconds later, when he connected on Gonzaga standing, the match was over in just 1:09.

Lesnar (4-1), the sport’s ultimate villain, has replaced the retired Oscar De La Hoya as the biggest pay-per-view draw in combat sports, putting up big numbers in all four of his UFC fights.

From a business standpoint, the match makes sense on several levels. Had the Carwin vs. Velasquez winner gotten the next shot, as White had talked about, Lesnar wouldn’t be available to fight until Super Bowl weekend at the earliest. Carwin vs. Velasquez would also eliminate the loser from possible contention.

The heavyweight division, in terms of depth, is the strongest in the history of the company, even after the failure to sign standout Fedor Emelianenko.

Besides Velasquez, in the wings as title contenders in early 2010 would include winners of the Aug. 29 fight in Portland, Ore., with former champions Randy Couture and Antonio Rodrigo Nogueira, as well as the winner of a Sept. 19 fight in Dallas between Cro Cop and Junior Dos Santos.